"Don't cheerleaders all over America form pyramids six to eight times a year. Is that torture?" Guy Womack, Graner's attorney, said in opening arguments to the 10-member U.S. military jury at the reservist sergeant's court-martial.

Graner and Pvt. Lynndie England, with whom he fathered a child and who is also facing a court-martial, became the faces of the Abu Ghraib prison scandal after they appeared in photographs that showed degraded, naked prisoners.

The prosecution showed some of those pictures in their opening argument, including several of naked Iraqi men piled on each other and another of England holding a crawling naked Iraqi man on a leash.

Womack said using a tether was a valid method of controlling detainees, especially those who might be soiled with feces.

"You're keeping control of them. A tether is a valid control to be used in corrections," he said. "In Texas we'd lasso them and drag them out of there." He compared the leash to parents who place tethers on their toddlers while walking in shopping malls.

Pictures of the humiliating treatment of the prisoners at the Abu Ghraib prison outside Baghdad prompted outrage around the world and further eroded the credibility of the United States already damaged in many countries by the 2003 Iraq invasion.

Apart from arguing that the methods were not illegal, Graner's defense is that he was following orders. "He was doing his job. Following orders and being praised for it," Womack told the court, adding later that Graner would testify in the case.

Initial witnesses described how Graner, wearing gloves, led several guards in stacking naked prisoners accused of leading a prison riot into a pyramid on November 8, 2003.

"That's Corp. Graner right there," Pvt. Jeremy Sivits, who is serving a year prison sentence for his role in the abuse, said as he pointed out Graner organizing naked prisoners into a pyramid.That night Graner also knocked out one of the hooded prisoners, an accused boy rapist, by punching the temple of his head, he said. "I told Corp. Graner, 'I think you knocked him out sir,"' said Sivits, who pleaded guilty at his court martial last year. "He obviously had to hit him pretty hard to knock him out."

He said Graner also commented out loud about how the punch had impacted his hand. "Oh, damn, that hurt," Sivits quoted Graner as saying.

Graner was later demoted to that of specialist.

Sivits also testified that Graner beat a prisoner recovering from a gunshot wound in December 2003. "Please mister, please, please, please stop," was the Iraqi's response, Sivits said.

PART OF WIDER ABUSE QUESTIONS

The Bush administration has said the actions were those of a small group and were not part of a policy or condoned by senior officers.

But investigations have shown many prisoners in Iraq, Afghanistan and at the U.S. Navy base at Guantanamo Bay in Cuba also suffered abusive treatment after the government considered ways to obtain information in the war against terrorism.

The trial of Graner, a former Pennsylvania civilian prison guard who chatted and joked with his defense attorneys before the hearing opened, was expected to last at least a week.

Defense attorney Womack said U.S. embarrassment over the Abu Ghraib photographs had prompted the charges against his client. "The embarrassment puts pressure on the government: how do we mollify the world and make them like us again?" he said.

Graner, 36, faces up to 17 1/2 years in prison on charges that include mistreating detainees, dereliction of duty and assault. He has pleaded not guilty.

Four of seven accused members of Graner's unit have already pleaded guilty to abuse charges and three have been sentenced to prison. Pvt. Ivan Frederick, who was sentenced to eight years in prison in the case, was scheduled to testify on Monday afternoon.